I still don't know why it's called "friendly fire" when the US soldiers kills a British soldier. What does the term actually mean? Does it mean oh they were being friendly and greeting them by launching a bomb on them? you know just as a fun and to show how friendly they are.

Anyways...

It is understood the soldiers were killed when US fighter planes dropped a bomb where MoD was patrolling. It was a F15 aircraft and the soldiers were declared dead at the scene.

Google Image of F15 Aircrafts